Pluto is now officially classified as a dwarf planet. It is one of the largest members of a class of icy spheres known as Kuiper Belt Objects. It has
known moons; one of which, Charon, is very large - almost as big as Pluto itself!

The surface of Pluto appears to be composed of a mixture of ice and rock, while its interior is probably similar to that of other icy moons in the solar system.
Surprisingly, Pluto does have an atmosphere which is continuously produced and lost while Pluto is within Neptune's orbit. No one knows yet if Pluto has a magnetosphere or not! Maybe we will find out when
NASA's New Horizon mission, which launched in 2006, makes it to Pluto in 2015!

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Do you know what a planet is? If so, you are doing better than professional astronomers! Right now astronomers aren't quite sure how to define a planet. Maybe you've heard that some astronomers think Pluto...more

Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); moons. One of the moons is very large. The large moon is named Charon. The other two moons are fairly small....more

Charon is a moon of Pluto. Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); moons. Charon is much larger than Pluto's other moons. James Christy discovered...more

The diagram to the left shows a cutaway of the possible interior structure of Pluto. The composition of Pluto is mostly ice, therefore there is probably a small core of some rocky material buried inside,...more

It may seem hard to believe that Pluto could have an atmosphere because it is so cold at 39 AU, where Pluto is found, but it does. Because there are times when Pluto is closer to the sun than is Neptune...more

No one knows whether or not Pluto has a magnetosphere. Scientists were very surprised to find that Jupiter's icy moon Ganymede had a magnetosphere because it is hard to explain how an icy body can develop...more